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dojox.gfx
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Version 1.100
Release date: 08/01/2006
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Project state:
beta
HTMLCanvas renderer: experimental
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Credits
Eugene Lazutkin (eugene.lazutkin@gmail.com)
Kun Xi (bookstack@gmail.com)
Chris Mitchell (ccmitchellusa@gmail.com) HTML Canvas
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Project description
Implementation of simple portable 2D graphics library.
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Dependencies:
Dojo Core
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Documentation
Currently it can be found here: http://docs.google.com/Doc?id=d764479_1hnb2tn
HTMLCanvas Renderer Status
To use canvas rendering, insert 'canvas' at the beginning of the gfxRenderers list in your
djConfig, for example:
<script type="text/javascript" src="../../../dojo/dojo.js"
djConfig="parseOnLoad: true, gfxRenderer: 'canvas,svg,silverlight,vml'"></script>
canvas currently will only render on non-IE browsers (see dojox/gfx.js for where the renderer is loaded);
although it should be possible to use an IE canvas implementation (like Google's); however, it will be very slow.
The following tests can be made to work with HTML Canvas with minor testcase modification:
dojox/gfx/tests
test_gfx.html-Bugs #1
test_arc.html
test_bezier.html
test_pattern.html
test_gradient.html
test_linearGradient.html
test_image1.html - Limitation #3
test_transform.html - Bug #1
test_poly.html - Bug #1
dojox/gfx/demos
butterfly.html - Bug #1
lion.html - Bug #1
tiger.html - Bug #1
circles.html - No event processing yet :(
creator.html
dojox/chart
test_pie2d.html - Dojo Charts on iPhone anyone? :)
test_chart2d.html -
// To make charts work, the following line needs to be added to the end of the
// Chart2D.js render() method (prior to return)
if(this.surface.render){this.surface.render()};
Known Limitations:
1) event handling- plan is to capture all events at canvas, perform intersect/hit
tests (not implemented) against scene graph, then propogate event to top-most
intersected shape. HtmlCanvas shape need intersectsStroke and intersectsBounds,
and intersects (region).
2) SVG and VML are "live" scene graphs; eg. any state change to objects in the
scene automatically get rendered in next engine render pass. For canvas, it's
procedural, and current implementation requires application to call surface.render()
whenever scene needs to be updated. Plan is to do dirty region checking based
on bounding boxes (currently not properly computed), and track dirty areas anytime
state changes (invalidate) separate from render phase.
Add the following call where changes to the scene graph are complete and you want to
render:
if (surface.render){surface.render();}
4) Text/Text Paths - Text shape is implemented using DIV overlays. Many text styles are not
applied, and outline/fills are not possible. This is due to limitations in Canvas spec.
Firefox 3.0 has proprietary text functions that we could test for and use once FF3 is out.
No luck on Safari.
3) No Image skewing - Limitation of Canvas
Known Bugs:
1) Matrix xformations (applied from root to shape leaf nodes) not quite right--but very close.
Canvas does not have a built in transformation function that allows skewing. Need to
track skew matrix with Shape, and perform other trans/rot/scale transformations without
using canvas transform functions.
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Installation instructions
Grab the following from the Dojo SVN Repository:
http://svn.dojotoolkit.org/var/src/dojo/dojox/trunk/gfx.js
http://svn.dojotoolkit.org/var/src/dojo/dojox/trunk/gfx/*
Install into the following directory structure:
/dojox/gfx/
...which should be at the same level as your Dojo checkout.
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